Heretofore, as dosage forms for agricultural pesticides, dusts and granules have been primarily used. Those dosage forms are prepared by formulating a small amount of a pesticidally active substance with a large amount of a carrier such as clay, bentonite, calcium carbonate, etc. and, therefore, such formulations must be applied in quantities as large as 2 to 6 kilograms/10 ares in order to insure a uniform distribution of the active substance. This imposes a great burden on the farmers and, moreover, there are many disadvantages in transportation and storage. For this reason, so-called concentrates, which are supplied in small packages to provide for a greater ease of handling, are being developed.
Those concentrates are rich in the active substances and can be applied after dispersion in a suitable diluent, such as water, in the field. Examples include emulsifiable concentrates and wettable powders. However, emulsifiable concentrates require large quantities of an organic solvent for dilution, while it is unavoidable with wettable powders that preparation of sprays in the field involves contaminations with flying solid particles. For those reasons, the recent trend is toward refraining from using those formulations. Wettable granules, which are granular versions of wettable powders have almost overcome the drawbacks of wettable powders but because the size of particles dispersed in water is as large as about 10 and odd .mu.m, application of a dispersion of high concentration causes clogging of the spray nozzle, among other disadvantages.
The compound of the formula (I): ##STR2##
or a salt thereof, is an agricultural pesticide having potent pest-controlling activity.
The demand exists today for development of a stable aqueous suspension of the compound (I) or a salt thereof which should have a low viscosity enough to permit smooth delivery from a container as well as satisfactory dispersibility in diluent water and long-term fluidity free from caking due to precipitation of the suspended particles.